1. Field of Invention
The invention relates to an electrical plug connector for connection of an electrical cable to an apparatus, and in particular to a sensor or an actuator, or for detachable connection of two electrical cables to one another, and having a housing, including a contact mount, which holds a variety of contacts, and an electronics circuit, which is arranged in the housing, with the electronics circuit having at least one light-emitting element, including an LED, and being electrically connected to the contacts.
2. Description of Related Art
Essentially, electrical plug connections are composed of two parts, the electrical plug connector and the mating plug connector. Electrical plug connections can either be used to connect an electrical cable to an electrical or electronic appliance, or to connect two cables to one another. In the first case, the mating plug connector is connected to the electrical housing, and in the second case it is connected to the cable. Both the plug connector and the mating plug connector each have a contact mount with corresponding contacts, which are either contact pins or the corresponding sockets. Dependent on whether the contact pins or sockets are arranged in the respective contact mount, the associated connecting part is referred to as a plug or a socket.
In the case of plug connections such as these, it is known for the plug connector and the mating plug connector to be mechanically connected to one another by, for example, arranging a union nut on the plug connector, which is screwed to the thread that is formed on the outer sleeve of the mating plug connector. In this case, the union nut then has an internal thread, which corresponds with the thread on the mating plug connector. However, as an alternative to this, it is also possible for a union screw to be arranged on the plug connector and to have an external thread, so that the plug connector with the union screw can be screwed into an outer sleeve, which has a corresponding internal thread, on the mating plug connector.
Electrical plug connections or plug connectors such as these are used in automation, as a component of electronic equipment, sensors, actuators and controllers. In this case, in particular, M12 and M8 types are in widespread use, with three, four, five or eight contacts, in which case the electrical plug connectors and mating plug connectors are known both in a straight form and in a form angled through 90°. In the case of the latter, the housing of the electrical plug connector is angled through 90°, so that there is an angle of 90° between the longitudinal direction of the connecting cable being held and the longitudinal direction of the contacts. Corresponding plug connections are known, for example, from the 2005 Catalogue “Positionssensorik or Position Sensor System,” pages 430-444 from ifm electronic, gmbh.
Electrical plug connectors such as these can either be connected as required or can be ready-wired, in which case the contact mount and the cable are extrusion-coated with the housing, which is then also referred to as a grip. Finally, electrical plug connectors may also be in the form of adapters, with the plug connector then having two contact mounts, which can each be connected to a corresponding mating contact mount. In this case, as a rule, a cable which has already been connected to a corresponding mating contact mount is connected at least to one contact mount, while the other contact mount is then generally connected to the mating contact mount of a device or apparatus.
Electrical plug connectors of the type described initially and which are used in particular for connection of an electrical connection to an appliance, in particular a sensor, also have, in addition to the contact mount, an electronics circuit having at least one light-emitting element, generally a light emitting diode (LED). The LEDs, of which there are up to three in practice, are in this case used to visually signal the serviceability and in particular the switching state of the connected sensor. For this purpose, either an appropriate window is formed in the housing, which is generally closed by a separate, transparent cover, or the housing is entirely composed of a transparent material. In this way, the light beams emitted from the LEDs can pass either through the transparent cover or through the transparent material of the housing, so that the status of the LED can be seen.
The first variant has the disadvantage that, first of all, the production is relatively complex and costly since the various parts, e.g., the housing and cover, must be produced and connected to one another, for example, by adhesive bonding or ultrasound welding. Furthermore, the two-part configuration means that sealing problems also can occur, so that, for applications in which the sealing of the housing is significant, the complexity and thus also the costs for production of a corresponding electrical plug connector can rise further.
For this reason, in practice, a transparent plastic increasingly is being used to produce the housing for electrical plug connectors having at least one LED. For applications in which the electrical plug connector is subject to strong external incident light, there is a problem, however, in that it is often no longer reliably possible to tell whether or not an LED is illuminated. Because of the transparent material that is used, it is also possible in particular in this case for reflections to occur of the light striking the plug connector from outside onto components arranged in the housing, wherein it is then virtually impossible to distinguish the reflected light from the light from the LED.